A variety of platform-as-a-service (PaaS) system offerings exist that include software and/or hardware facilities for facilitating the execution of web applications in a cloud-computing environment (the “cloud”). Cloud computing is a computing paradigm in which a customer pays a “cloud provider” to execute a program on computer hardware owned and/or controlled by the cloud provider. It is common for cloud providers to make virtual machines (VMs) hosted on its computer hardware available to customers for this purpose.
The cloud provider typically provides an interface that a customer can use to requisition virtual machines and associated resources such as processors, storage, and network services, as well as an interface a customer can use to install and execute the customer's program on the virtual machines that the customer requisitions, together with additional software on which the customer's program depends. For some such programs, this additional software can include software components, such as a kernel and an operating system, and/or middleware and a framework. Customers that have installed and are executing their programs “in the cloud” typically communicate with the executing program from remote geographic locations using Internet protocols.
PaaS offerings facilitate deployment of web applications without the cost and complexity of buying and managing the underlying hardware and software and provisioning hosting capabilities, providing the facilities to support the complete life cycle of building and delivering web applications and services entirely available from the Internet. Typically, these facilities operate as one or more VMs running on top of a hypervisor in a host server.